Charging method, terminal, charger, and system

ABSTRACT

A charging method, a terminal, a charger, and a system, includes: obtaining, by a terminal, a charging mode supported by a charger connected to the terminal; when the charging mode supported by the charger includes an open-loop fast charging mode, detecting, by the terminal, whether both the terminal and the charger are in an open loop state; when both the terminal and the charger are in the open loop state, sending, by the terminal, an open-loop fast charging instruction to the charger; and receiving, by the terminal, a voltage and a current that are transmitted by the charger according to the open-loop fast charging instruction, and performing charging in the open-loop fast charging mode. When determining that the charger supports charging in the open-loop fast charging mode, the terminal is adjusted to the open loop state to perform charging, so as to shorten a charging time and improve user experience.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/197,471, filed on Nov. 21, 2018, which is a continuation ofInternational Application No. PCT/CN2017/085142, filed on May 19, 2017.The International Application claims priority to Chinese PatentApplication No. 201610350094.4, filed on May 24, 2016. All of theafore-mentioned patent applications are hereby incorporated by referencein their entireties.

TECHNICAL FIELD

The present application relates to charging technologies, and inparticular, to a charging method, a terminal, a charger, and a system.

BACKGROUND

With the development of science and technology, a function of a terminalbecomes more powerful, and a user can work and have entertainment byusing the terminal, so that the terminal has become an indispensablepart of people's daily life. However, a battery life of the terminal islimited, and the user needs to continuously charge the terminal.

However, with a larger capacity and higher density of a battery equippedin the terminal, a charging time of the terminal becomes longer, so thatnormal use of the terminal by the user is severely affected and userexperience is relatively poor.

SUMMARY

Embodiments of the present application provide a charging method, aterminal, a charger, and a system, so as to fast charge the terminal,thereby improving user experience.

A first aspect of the present application provides a charging method,where the method includes: obtaining, by a terminal, a charging modesupported by a charger connected to the terminal; when the charging modesupported by the charger includes an open-loop fast charging mode,detecting, by the terminal, whether both the terminal and the chargerare in an open loop state; when both the terminal and the charger are inthe open loop state, sending, by the terminal, an open-loop fastcharging instruction to the charger; and receiving, by the terminal, avoltage and a current that are transmitted by the charger according tothe open-loop fast charging instruction, and performing charging in theopen-loop fast charging mode.

It may be understood that if the charger is not in the open loop state,the terminal may send a status adjustment instruction to the charger, sothat the charger adjusts a charging state to the open loop stateaccording to the status adjustment instruction. It should be noted thatthe charger can support the open-loop fast charging mode only when thecharger is in the open loop state.

It should be noted that the terminal may further detect whether abattery status reaches a preset status, for example, a state of chargeand a health state.

It may be understood that the open-loop fast charging instruction mayinclude a plurality of parameter combinations, and is specifically asfollows:

Optionally, the open-loop fast charging instruction includes a batteryvoltage value of the terminal and a target voltage value of theterminal, and the open-loop fast charging instruction is used toinstruct the charger to output a voltage of the target voltage value andoutput a current according to the battery voltage value; and

the performing, by the terminal, charging in the open-loop fast chargingmode includes:

converting, by the terminal, the received voltage into a 1/K timescharging voltage, and converting the received current into a K timescharging current, where a conversion coefficient K is a constant value,and K is any real number greater than 1; and

charging, by the terminal, a battery according to the 1/K times chargingvoltage and the K times charging current.

Optionally, the open-loop fast charging instruction includes a targetvoltage value and a target current value, and the open-loop fastcharging instruction is used to instruct the charger to output a voltageof the target voltage value and a current of the target current value;and

the performing, by the terminal, charging in the open-loop fast chargingmode includes:

converting, by the terminal, the received voltage into a 1 /K timescharging voltage, and converting the received current into a K timescharging current, where a conversion coefficient K is a constant value,and K is any real number greater than 1; and

charging, by the terminal, a battery according to the 1/K times chargingvoltage and the K times charging current.

Optionally, the open-loop fast charging instruction includes a batteryvoltage value of the terminal, and the open-loop fast charginginstruction is used to instruct the charger to output, according to thebattery voltage value, a voltage and a current; and

adaptively, the performing, by the terminal, charging in the open-loopfast charging mode includes:

converting, by the terminal, the received voltage into a 1/K timescharging voltage, and converting the received current into a K timescharging current, where a conversion coefficient K is a constant value,and K is any real number greater than 1; and

charging, by the terminal, a battery according to the 1/K times chargingvoltage and the K times charging current.

It may be understood that the charger may support two or more chargingmodes. Optionally, when the charging mode supported by the chargerfurther includes the closed-loop fast charging mode, the method furtherincludes: detecting a voltage of the battery in the terminal to obtainthe battery voltage value; when the battery voltage value is greaterthan a first preset threshold, sending a closed-loop fast charginginstruction to the charger; and receiving, by the terminal, a voltageand a current that are transmitted by the charger according to theclosed-loop fast charging instruction, and performing charging in theclosed-loop fast charging mode. It should be noted that when the batteryvoltage value is greater than the first preset threshold, theclosed-loop fast charging mode may be used to perform refined chargingaccording to real-time voltage feedback of the battery. It may beunderstood that before the performing charging in the closed-loop fastcharging mode, the method further includes: switching, by the terminal,the charging mode from the open-loop fast charging mode to theclosed-loop fast charging mode.

Optionally, when the charging mode supported by the charger furtherincludes the closed-loop fast charging mode, the method furtherincludes: detecting a voltage of the battery in the terminal to obtainthe battery voltage value; when the battery voltage value is greaterthan a second preset threshold, sending a common charging instruction tothe charger; and receiving, by the terminal, a voltage and a currentthat are transmitted by the charger according to the common charginginstruction, and performing charging in the common fast charging mode.

With reference to the first aspect, it should be noted that theobtaining, by a terminal, a charging mode supported by a chargerconnected to the terminal includes: detecting, by the terminal, avoltage signal of a communication cable between the terminal and thecharger, so as to determine the charging mode supported by the charger.

With reference to the first aspect, it should be noted that, before theobtaining, by a terminal, a charging mode supported by a chargerconnected to the terminal, the method further includes: sending, by theterminal, a request message to the charger connected to the terminal,where the request message is used to obtain the charging mode supportedby the charger; and

the obtaining, by a terminal, a charging mode supported by a chargerconnected to the terminal includes:

receiving, by the terminal, a feedback message sent by the charger,where the feedback message includes the charging mode supported by thecharger.

A second aspect of the present application provides another chargingmethod, where the method includes: when a charger detects that aconnection is established to a terminal, performing, by the charger, ahandshake with the terminal, so that the terminal determines that thecharger supports an open-loop fast charging mode; receiving, by thecharger, instruction information sent by the terminal; and when theinstruction information is used to instruct the charger to charge in theopen-loop fast charging mode, outputting, by the charger, a voltage anda current according to the instruction information in the open-loop fastcharging mode.

With reference to the second aspect, it should be noted that a methodfor implementing this step: the performing, by the charger, a handshakewith the terminal, so that the terminal determines that the chargersupports an open-loop fast charging mode, may be: setting, by thecharger, a voltage signal of a communication cable, so that the terminaldetermines, according to the voltage signal, that the charger supportsthe open-loop fast charging mode. Optionally, a method for implementingthis step may also be: receiving, by the charger, an inquiry requestsent by the terminal, where the inquiry request is used to obtain acharging mode supported by the charger; and sending, by the charger,feedback information to the terminal, where the feedback information isused to indicate that the charger supports a fast charging mode.

With reference to the second aspect, it may be understood that theinstruction information may include various information, and isspecifically as follows:

Optionally, the instruction information includes a battery voltage valueof the terminal; and

the outputting, by the charger, a voltage and a current according to theinstruction information in the open-loop fast charging mode includes:

adjusting, by the charger, the voltage to K times the battery voltagevalue, where K is a pre-stored fixed conversion ratio coefficient, and Kis a constant value and is any real number greater than 1;

determining, by the charger, a current corresponding to the batteryvoltage value, where a correspondence between the battery voltage valueand the current is pre-stored in the charger; and

outputting, by the charger, a voltage of the K times the battery voltagevalue, and outputting the current corresponding to the battery voltagevalue.

Optionally, the instruction information includes a battery voltage valueof the terminal and a target voltage value of the terminal; and

the outputting, by the charger, a voltage and a current according to theinstruction information in the open-loop fast charging mode includes:

adjusting, by the charger, the voltage to the target voltage value;

determining, by the charger, a current value corresponding to thebattery voltage value, where a correspondence between the batteryvoltage value and the current is pre-stored in the charger; and

outputting, by the charger, a voltage of the target voltage value, andoutputting the current corresponding to the battery voltage value.

Optionally, the instruction information includes the target voltagevalue and a target current value; and

the outputting, by the charger, a voltage and a current according to theinstruction information in the open-loop fast charging mode includes:

adjusting, by the charger, the voltage to the target voltage value;

adjusting, by the charger, the current to the target current value; and

outputting, by the charger, a voltage of the target voltage value and acurrent of the target current value.

A third aspect of the present application provides a terminal, where theterminal includes: an obtaining unit, configured to obtain a chargingmode supported by a charger connected to the terminal; a detection unit,configured to: when the charging mode supported by the charger includesan open-loop fast charging mode, detect, by the terminal, whether boththe terminal and the charger are in an open loop state; a sending unit,configured to: when both the charger and the terminal are in the openloop state, send, by the terminal, an open-loop fast charginginstruction to the charger; a receiving unit, configured to receive avoltage and a current that are transmitted by the charger according tothe open-loop fast charging instruction; and a charging unit, configuredto perform charging in the open-loop fast charging mode.

With reference to the third aspect, it may be understood that theopen-loop fast charging instruction may include a plurality of groups ofparameters, and is specifically as follows:

Optionally, the open-loop fast charging instruction includes a batteryvoltage value of the terminal and a target voltage value of theterminal, and the open-loop fast charging instruction is used toinstruct the charger to output a voltage of the target voltage value andoutput a current according to the battery voltage value;

the charging unit is configured to: convert the received voltage into a1/K times output voltage, and convert the received output current into aK times output current, where a conversion coefficient K is a constantvalue, and K is any real number greater than 1; and

the charging unit is further configured to charge a battery according tothe 1/K times output voltage and the K times output current.

Optionally, the open-loop fast charging instruction includes a targetvoltage value and a target current value, and the open-loop fastcharging instruction is used to instruct the charger to output a voltageof the target voltage value and a current of the target current value;the charging unit is configured to: convert the received voltage into a1/K times output voltage, and convert the received output current into aK times output current, where a conversion coefficient K is a constantvalue, and K is any real number greater than 1; and

the charging unit is further configured to charge a battery according tothe 1/K times output voltage and the K times output current.

Optionally, the open-loop fast charging instruction includes a batteryvoltage value of the terminal, the open-loop fast charging instructionis used to instruct the charger to output, according to the batteryvoltage value, a voltage and a current; the charging unit is configuredto: convert the received voltage into a 1/K times output voltage, andconvert the received output current into a K times output current, wherea conversion coefficient K is a constant value, and K is any real numbergreater than 1; and

the charging unit is further configured to charge a battery according tothe 1/K times output voltage and the K times output current.

With reference to the third aspect, it should be noted that thedetection unit is further configured to: when the charging modesupported by the charger further includes the closed-loop fast chargingmode, detect a voltage of the battery in the terminal to obtain thebattery voltage value; the sending unit is configured to: when thebattery voltage value is greater than a first preset threshold, send aclosed-loop fast charging instruction to the charger; the receiving unitis further configured to receive a voltage and a current that aretransmitted by the charger according to the closed-loop fast charginginstruction; and the charging unit is configured to perform charging inthe closed-loop fast charging mode.

Optionally, the terminal further includes a switching unit, where theswitching unit is configured to switch the charging mode from theopen-loop fast charging mode to the closed-loop fast charging mode; andthe charging unit is configured to perform charging in the closed-loopfast charging mode.

With reference to the third aspect, it should be noted that thedetection unit is further configured to: when the charging modesupported by the charger further includes the common charging mode,detect a voltage of the battery in the terminal to obtain the batteryvoltage value; the sending unit is configured to: when the batteryvoltage value is greater than a second preset threshold, send a commoncharging instruction to the charger; the receiving unit is configured toreceive a voltage and a current that are transmitted by the chargeraccording to the common charging instruction; and the charging unit isconfigured to perform charging in the common fast charging mode.

Optionally, the terminal further includes a switching unit, where theswitching unit is configured to switch the charging mode from theopen-loop fast charging mode to the common charging mode; and thecharging unit is configured to perform charging in the common chargingmode.

With reference to the third aspect, it should be noted that theobtaining unit is configured to detect a voltage signal of acommunication cable between the terminal and the charger, so as todetermine the charging mode supported by the charger.

With reference to the third aspect, it may be understood that thesending unit is configured to send a request message to a chargerconnected to the terminal, where the request message is used to obtainthe charging mode supported by the charger; and the obtaining unit isconfigured to receive a feedback message sent by the charger, where thefeedback message includes the charging mode supported by the charger.

A fourth aspect of the present application provides a charger, where thecharger includes: a handshake unit, configured to: when a chargerdetects that a connection is established to a terminal, perform ahandshake with the terminal, so that the terminal determines that thecharger supports an open-loop fast charging mode; a receiving unit,configured to receive instruction information sent by the terminal; andan output unit, configured to: when the instruction information is usedto instruct the charger to charge in the open-loop fast charging mode,output, by the charger, a voltage and a current according to theinstruction information in the open-loop fast charging mode.

With reference to the fourth aspect, it should be noted that thehandshake unit is further configured to set a voltage signal of acommunication cable, so that the terminal determines, according to thevoltage signal, that the charger supports the open-loop fast chargingmode.

With reference to the fourth aspect, it may be understood that thereceiving unit is further configured to receive an inquiry request sentby the terminal, where the inquiry request is used to obtain a chargingmode supported by the charger; and the handshake unit is furtherconfigured to send feedback information to the terminal, where thefeedback information is used to indicate that the charger supports afast charging mode.

With reference to the fourth aspect, it should be noted that theinstruction information may include a plurality of groups of parameters,and is specifically as follows:

Optionally, the instruction information includes a battery voltage valueof the terminal;

the output unit is configured to: adjust the voltage to K times thebattery voltage value, and output a voltage of the K times the batteryvoltage value, where K is a pre-stored fixed conversion ratiocoefficient, and K is a constant value and is any real number greaterthan 1; and

the output unit is further configured to: determine a currentcorresponding to the battery voltage value, and output the currentcorresponding to the battery voltage value, where a correspondencebetween the battery voltage value and the current is pre-stored in thecharger.

Optionally, the instruction information includes a battery voltage valueof the terminal and a target voltage value of the terminal;

the output unit is configured to: adjust the voltage to the targetvoltage value, and output a voltage of the target voltage value; and

the output unit is further configured to: determine a current valuecorresponding to the battery voltage value, and output the currentcorresponding to the battery voltage value, where a correspondencebetween the battery voltage value and the current is pre-stored in thecharger.

Optionally, the instruction information includes the target voltagevalue and a target current value;

the output unit is configured to: adjust the voltage to the targetvoltage value, and output a voltage of the target voltage value; and

the charger adjusts the output current to the target current value, andoutputs a current of the target current value.

A fifth aspect of the present application provides a charging system,where the charging system includes a connection cable, the terminalaccording to the third aspect, and the charger according to the fourthaspect, where the terminal is connected to the charger by using theconnection cable.

A sixth aspect of the present application provides another chargingmethod, and the charger may identify a charging mode supported by aterminal. When the terminal supports an open-loop fast charging mode,the charger instructs the terminal to adjust to an open loop state, andthe charger obtains a charging parameter of the terminal, adjusts avoltage and a current according to the charging parameter, and outputsan adjusted voltage and an adjusted current. The charging parameter maybe a battery voltage value, or may be a battery voltage value and atarget current value, or may be a target voltage value and a targetcurrent value.

Optionally, the charger obtains the charging mode supported by theterminal connected to the charger. When the charging mode supported bythe terminal includes the open-loop fast charging mode, the chargerdetects whether both the terminal and the charger are in the open loopstate. When the terminal is in the open loop state, the charger obtainsa target voltage and a target current of the terminal. The chargeroutputs the target voltage and the target current, so that the terminalperforms charging in the open-loop fast charging mode.

A seventh aspect of the present application provides a terminal, wherethe terminal includes a first detection circuit, a second detectioncircuit, a sending circuit, a receiver circuit, and a charging circuit.

The first detection circuit is configured to detect a voltage signal ofa communication cable between the terminal and a charger, so as todetermine a charging mode supported by the charger.

It should be noted that the terminal may further obtain, by means ofinteraction, the charging mode supported by the charger. For example,the sending circuit sends a request message to the charger connected tothe terminal, where the request message is used to obtain the chargingmode supported by the charger. The receiving circuit is configured toreceive a feedback message sent by the charger, where the feedbackmessage includes the charging mode supported by the charger.

The second detection circuit is configured to: when the charging modesupported by the charger includes an open-loop fast charging mode,detect, by the terminal, whether both the terminal and the charger arein an open loop state.

The sending circuit is configured to: when both the charger and theterminal are in the open loop state, send, by the terminal, an open-loopfast charging instruction to the charger.

The receiving circuit is configured to receive a voltage and a currentthat are transmitted by the charger according to the open-loop fastcharging instruction.

The charging circuit is configured to perform charging in the open-loopfast charging mode.

It should be noted that the charging circuit is specifically configuredto: convert the received voltage into a 1 /K times charging voltage, andconvert the received current into a K times charging current, where aconversion coefficient K is a constant value, K is any real numbergreater than 1; and the charging circuit is further configured to chargea battery according to the 1/K times charging voltage and the K timescharging current.

Optionally, the terminal further includes a third detection unit and aswitching circuit, where when the charging mode supported by the chargerfurther includes the closed-loop fast charging mode, the third detectionunit is configured to detect a voltage of the battery in the terminal toobtain a battery voltage value; the sending circuit is configured to:when the battery voltage value is greater than a first preset threshold,send a closed-loop fast charging instruction to the charger; thereceiving circuit is configured to receive a voltage and a current thatare transmitted by the charger according to the closed-loop fastcharging instruction; the switching circuit is configured to switch thecharging mode from the open-loop fast charging mode to the closed-loopfast charging mode; and the charging circuit is configured to performcharging in the closed-loop fast charging mode.

It should be noted that, when the charging mode supported by the chargerfurther includes the common charging mode, a method for switching theopen-loop fast charging mode to the common charging mode is the same asa method for switching the open-loop fast charging mode to theclosed-loop charging mode, and details are not repeatedly describedherein.

A eighth aspect of the present application provides a charger, where thecharger includes: a voltage setting circuit, a receiving circuit, and anoutput circuit. The voltage setting circuit is configured to set avoltage signal of a communication cable, so that the terminaldetermines, according to the voltage signal, that the charger supportsthe open-loop fast charging mode; the receiving circuit is configured toreceive instruction information sent by a terminal 10; and the outputcircuit is configured to: when the instruction information is used toinstruct a charger 20 to charge in the open-loop fast charging mode,output a voltage and a current according to the instruction informationin the open-loop fast charging mode.

Optionally, the charger may further notify, by means of interaction, theterminal of the charging mode supported by the charger. For example, thecharger further includes a sending circuit. The receiving circuit isconfigured to receive an inquiry request sent by the terminal, where theinquiry request is used to obtain a charging mode supported by thecharger; and when the receiving unit receives the inquiry request, thesending circuit sends feedback information to the terminal, where thefeedback information is used to indicate that the charger supports afast charging mode.

It can be learned from the foregoing that the technical solutions of thepresent application provide the charging method, the terminal, thecharger, and the system. In the technical solutions provided in thepresent application, the terminal obtains the charging mode supported bythe charger connected to the terminal. When the charging mode supportedby the charger includes the open-loop fast charging mode, the terminaldetects whether both the terminal and the charger are in the open loopstate. When the charger is in the open loop state, the terminal sendsthe open-loop fast charging instruction to the charger. The terminalreceives the voltage and the current that are transmitted by the chargeraccording to the open-loop fast charging instruction, and performscharging in the open-loop fast charging mode. By implementing thetechnical solutions provided in the present application, whendetermining that the charger supports charging in the open-loop fastcharging mode, the terminal is adjusted to the open-loop fast chargingmode to perform charging, so as to shorten a charging time and improveuser experience.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentapplication more clearly, the following briefly describes theaccompanying drawings required for describing the embodiments of thepresent application. Apparently, the accompanying drawings in thefollowing description show merely some embodiments of the presentapplication, and a person of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is a schematic diagram of a fast charging system according to anembodiment of the present application;

FIG. 2 is a flowchart of a charging method according to an embodiment ofthe present application;

FIG. 3 is a flowchart of another charging method according to anembodiment of the present application;

FIG. 4 is a flowchart of another charging method according to anembodiment of the present application;

FIG. 5 is a flowchart of another charging method according to anembodiment of the present application;

FIG. 6 is a flowchart of another charging method according to anembodiment of the present application;

FIG. 7 is a schematic structural diagram of a terminal according toanother embodiment of the present application;

FIG. 8 is a structural diagram of a detection circuit of a terminalaccording to an embodiment of the present application;

FIG. 9 is a Buck circuit diagram according to an embodiment of thepresent application;

FIG. 10 is a circuit diagram of a switched capacitor converter accordingto another embodiment of the present application;

FIG. 11 is a schematic structural diagram of a charger according to anembodiment of the present application;

FIG. 12 is a schematic diagram of a fast charging system according toanother embodiment of the present application; and

FIG. 13 is a structural diagram of a switched capacitor converteraccording to another embodiment of the present application.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present application with reference to theaccompanying drawings in the embodiments of the present application.Apparently, the described embodiments are some but not all of theembodiments of the present application. All other embodiments obtainedby a person of ordinary skill in the art based on the embodiments of thepresent application without creative efforts shall fall within theprotection scope of the present application.

As a terminal continues to become strong, people are increasinglydependent on the terminal, and even do not leave the terminal for amoment. People can perform communication, have entertainment, work, anddo the like by using the terminal. Therefore, the terminal plays animportant role in daily life. A subsequent problem is that a largequantity of applications are running for a long time at the same time,resulting in relatively fast power consumption of the terminal, and alarge capacity and high density of a battery configured in the terminalcause a relatively low charging speed, and severely affect a user's use,so as to reduce user experience.

The present application provides a fast charging system, and the fastcharging system can implement fast charging. For a specific schematicdiagram of the fast charging system, refer to FIG. 1 . The systemincludes a terminal 10, a charger 20, and a connection cable 30, wherethe terminal 10 is connected to the charger 20 by using the connectioncable 30.

It should be noted that, as shown in FIG. 2 , the system performs thefast charging by using the following procedure.

S101. A terminal 10 is configured to obtain a charging mode supported bya charger 20 connected to the terminal 10.

The terminal 10 may be an electronic device such as a mobile phone, atablet computer, an intelligent wearable device, and a computer.

A battery in the terminal is usually a lithium-ion battery, and a typeof the battery is not limited herein.

The terminal 10 may detect a voltage signal of a communication cablebetween the terminal 10 and the charger 20, so as to determine thecharging mode supported by the charger.

Optionally, in addition to a connection cable between the terminal 10and the charger 20, there may further be separate communication cables(two cables: D+ and D−). For example, different types of chargersgenerally provide a parameter such as a charging type by applyingdifferent voltages to D+ and D−, and the terminal 10 detects the voltagesignal of the communication cable to determine the charging modesupported by the charger 20. As shown in the following table, whendetecting that D+ is 0.6 V and D− is 0 V, the terminal considers that acharger supports a common charging mode. When detecting that D+ is 3.3 Vand D− is 0.6 V, the terminal considers that a charger supports 9 V 2 Acharging. When detecting that D+ is 0.6 V and D− is 3.3 V, the terminalconsiders that a charger supports open-loop fast charging.

Maximum D+ D− Output voltage output current 0.6 V 0 V 5 V 1 A 0.6 V 0.6V 12 V  1.5 A 3.3 V 0.6 V 9 V 2 A 0.6 V 3.3 V Open-loop charging mode 9A

It should be noted that the terminal 10 may further obtain, by means ofinteraction, the charging mode supported by the charger 20, and themeans of interaction may be wireless communications (both the terminaland the charger have a wireless communications module, for example,Wireless Fidelity Wi-Fi, Bluetooth, and Zigbee). For example, a specificinteraction process may be as follows: The terminal 10 sends a requestmessage to the charger 20 connected to the terminal 10, where therequest message is used to obtain the charging mode supported by thecharger 20; and the terminal 10 receives a feedback message sent by thecharger 20, where the feedback message includes the charging modesupported by the charger 20.

It may be understood that the connection cable between the terminal 10and the charger 20 integrates a communication function, and may transferinformation between the terminal 10 and the charger 20.

S102. When the charging mode supported by the charger 20 includes anopen-loop fast charging mode, the terminal 10 is configured to detectwhether both the terminal 10 and the charger 20 are in an open loopstate.

It may be understood that the terminal 10 may include a plurality ofcharging modes, for example, the open-loop charging mode, a closed-loopcharging mode, or the common charging mode. Therefore, there is a needto detect whether the terminal 10 is in the open loop state, and thisspecifically indicates whether a DC/DC (DC/DC) conversion module in theterminal 10 works in the open loop state. It should be noted that theDC/DC module converts a current transmitted by the charger into acurrent that charges the battery.

It should be noted that the open-loop charging mode means that theterminal performs charging in a DC/DC conversion manner with a fixedconversion ratio, that is, the DC/DC module uses a fixed duty cycle towork, and continuously adjusts an output voltage and an output currentof the charger based on real-time voltage feedback of the battery.Conversion efficiency of the DC/DC conversion manner is higher, so thata charging current that is output to the battery on a mobile phone sidecan be larger, and charging efficiency of the entire fast chargingsystem is effectively improved, thereby effectively shortening acharging time.

It should be noted that the closed-loop charging mode means that theterminal performs charging in a DC/DC conversion manner with anpre-determined conversion ratio.

Likewise, the charger 20 may support one charging mode, or may includethe plurality of charging modes, for example, the open-loop chargingmode, the closed-loop charging mode, or the common charging mode.Therefore, there is a need to detect whether the charger 20 is in theopen loop state. When the charger 20 is in the open loop state, thecharger 20 may send information to the terminal 10 for notification, sothat the terminal 10 determines that the charger 20 is in the open loopstate.

Optionally, when the charging mode supported by the charger 20 includesthe open-loop fast charging mode, the terminal 10 detects whether theDC/DC module of the terminal works in the open loop state. If the DC/DCmodule does not work in the open loop state, the DC/DC module isadjusted to work in the open loop state, so as to perform charging inthe open loop mode.

Optionally, when the charging mode supported by the charger 20 includesthe open-loop fast charging mode and the closed-loop fast charging mode,the DC/DC module of the terminal may be first adjusted to the open loopstate, so as to perform charging in the open-loop fast charging mode.When a battery voltage in the terminal reaches a first preset threshold,the DC/DC module of the terminal is adjusted to a closed loop state, soas to perform charging in the closed-loop fast charging mode.

S103. When both the charger 20 and the terminal 10 are in the open loopstate, the terminal 10 is configured to send an open-loop fast charginginstruction to the charger.

It should be noted that the open-loop fast charging instruction mayenable, by transmitting a plurality of parameters, the charger 20 toperform charging.

For example, the open-loop fast charging instruction includes a batteryvoltage value and a target voltage value of the terminal 10, and is usedto instruct the charger 20 to output a voltage of the target voltagevalue and output a current according to the battery voltage value.

For another example, the open-loop fast charging instruction includes atarget voltage value and a target current value, and is used to instructthe charger 20 to output a voltage of the target voltage value and acurrent of the target current value.

For another example, the open-loop fast charging instruction includes abattery voltage value of the terminal 10, and is used to instruct thecharger to output a voltage and a current according to the batteryvoltage value.

S104. When receiving the open-loop fast charging instruction sent by theterminal 10, the charger 20 is configured to output a voltage and acurrent according to the instruction in the open-loop fast chargingmode.

It should be noted that when the instruction information includes thebattery voltage value of the terminal 10, the charger 20 adjusts thevoltage to K times the battery voltage value, where K is a pre-storedfixed conversion ratio coefficient, and K is a constant value and is anyreal number greater than 1; the charger 20 determines a currentcorresponding to the battery voltage value, where a correspondencebetween the battery voltage value and the current is pre-stored in thecharger 20; and the charger 20 outputs a voltage of the K times thebattery voltage value, and outputs the current corresponding to thebattery voltage value.

It may be understood that when the instruction information includes thebattery voltage value and the target voltage value of the terminal, thecharger 20 adjusts the voltage to the target voltage value; the charger20 determines a current value corresponding to the battery voltagevalue, where a correspondence between the battery voltage value and thecurrent is pre-stored in the charger; and the charger 20 outputs avoltage of the target voltage value, and outputs the currentcorresponding to the battery voltage value.

Optionally, when the instruction information includes the target voltagevalue and the target current value, the charger adjusts the voltage tothe target voltage value; the charger adjusts the current to the targetcurrent value; and the charger outputs a voltage of the target voltagevalue and a current of the target current value.

S105. The terminal 10 is configured to: receive the voltage and thecurrent that are transmitted by the charger 20 according to theopen-loop fast charging instruction, and perform charging in theopen-loop fast charging mode.

It should be noted that the performing, by the terminal, charging in theopen-loop fast charging mode includes:

converting, by the terminal 10, the received voltage into a 1/K timescharging voltage, and converting the received current into a K timescharging current, where a conversion coefficient K is a constant value,and K is any real number greater than 1; and charging, by the terminal10, the battery according to the 1/K times charging voltage and the Ktimes charging current. It may be understood that K and 1/K aretheoretical values obtained according to conservation of energy.However, a heat loss exists in a charging process, that is, thecharging, by the terminal 10, the battery according to the 1/K timescharging voltage and the K times charging current may be understood asfollows: The terminal 10 charges the battery according to a chargingvoltage close to the 1/K times charging voltage (for example, 95% to 99%of the 1/K times charging voltage) and a charging current close to the Ktimes charging current (for example, 95% to 99% of the K times chargingcurrent).

It may be understood that, when the terminal in the fast charging systemprovided in this embodiment of the present application determines thatthe charger supports the open-loop fast charging mode, fast charging canbe performed for the terminal in the open-loop fast charging mode,thereby improving user experience.

As shown in FIG. 3 , in another embodiment of the present application, aspecific charging method is provided, and the method may be applied tothe fast charging system described in FIG. 1 . The method includes thefollowing steps.

S201. A terminal 10 determines a connection status to a charger 20 and abattery status of the terminal 10.

The connection status may be understood that whether a connection can bepowered on, and whether communication can be performed, and the like.For the battery status, there is usually a need to determine whether abattery is well connected to the terminal, a state of charge of thebattery, a health status of the battery, and the like.

S202. The terminal 10 communicates with the charger 20 to determine acharging mode supported by the charger 20.

It should be noted that the terminal may actively send information tothe charger for inquiry, or may enable the charger to actively reportthe charging mode supported by the charger.

S203. When determining that the charger 20 supports an open-loop fastcharging mode, the terminal 10 adjusts a charging mode of the terminal10 to the open-loop fast charging mode, and sends a working statusadjustment instruction to the charger 20.

It should be noted that, if the terminal 10 is in the open-loop fastcharging mode, no adjustment is required.

S204. The charger 20 adjusts a working status to an open loop stateaccording to the working status adjustment instruction sent by theterminal 10.

It should be noted that, if the charger 20 is in the open-loop state, noadjustment is required.

S205. The charger 20 obtains a measured voltage and current of a batteryin the terminal 10.

S206. The charger 20 adjusts an output voltage and an output current ofthe charger according to a charging curve stored in a storage module andthe obtained measured voltage and current of the battery.

S207. The terminal 10 converts the received voltage and the receivedcurrent in the open-loop fast charging mode, and uses a convertedvoltage and a converted current to perform charging.

Optionally, when the charger 20 does not support the open-loop fastcharging mode, the charger outputs a preset voltage value, so that theterminal 10 performs charging according to the preset voltage value.

It may be understood that when it is detected that a voltage of thebattery in the terminal 10 reaches a preset threshold, the charger 20and the terminal 10 disconnect an electrical connection to stopcharging. For example, if the battery is fully charged with a voltage of4.5 V, when it is detected that a battery voltage reaches 4.49 V or 4.48V, charging may be stopped. The foregoing number is not limited, and isnot enumerated one by one.

As shown in FIG. 4 , in another embodiment of the present application, aspecific charging method is provided, and the method may be applied tothe fast charging system described in FIG. 1 . The method includes thefollowing steps.

S301. A terminal 10 detects a voltage signal of a communication cable toobtain a charging mode supported by a charger 20. It should be notedthat the communication cable connects the terminal 10 and the charger20.

S302. When the charging mode supported by the charger 20 includes anopen-loop fast charging mode, the terminal 10 is adjusted to an openloop state, and sends an open-loop fast charging instruction to thecharger, so that the charger 20 outputs a voltage and a current in theopen-loop fast charging mode.

It should be noted that when the terminal is in the open loop state, theterminal works according to a preset fixed maximum duty cycle (which,for example, may be a maximum duty cycle, thereby improving chargingefficiency), depends on a charger side to adjust an output voltage andimplement fast charging, and can perform charging with a relativelylarge charging current, so as to shorten a charging time.

In addition, it should be further noted that when charging is performedin the open-loop fast charging mode, the fast charging system performsfast charging in a high voltage and low current manner, and a relativelysmall charging current in a connection cable and a charging circuitreduces a requirement for the connection cable, and also reduces heat ofa charging system.

S303. When the charging mode supported by the charger 20 does notinclude the open-loop fast charging mode but includes a closed-loop fastcharging mode, the terminal 10 is adjusted to a closed loop state, andperforms charging according to a detected battery voltage, a chargingcurrent, and a pre-stored charging curve.

It should be noted that when the terminal is in the closed loop state,charging can be implemented by using a standard such as 9 V 2 A or 5 V1.8 A, and is compatible with another charging protocol.

It should be noted that when a battery voltage value of the terminal 10reaches a third preset threshold (the third preset threshold is close toa voltage value of a battery in a fully charged state, for example, maybe 99% of the voltage value of the battery in the fully charged state),the charger 20 is notified to stop charging.

It can be learned from the foregoing that the fast charging systemprovided in the present application is compatible with different inputvoltages and different chargers, and uses different control policies fordifferent input voltages or chargers. When the charger can perform fastcharging, the fast charging system uses an open-loop control manner,uses a fixed duty cycle to work, and continuously adjusts the outputvoltage and the output current of the charger based on real-time voltagefeedback of the battery. When the charger cannot perform fast charging,the fast charging system uses a closed-loop control manner, andcontinuously adjusts the output voltage and the output current of thecharger based on real-time voltage feedback of the battery.

As shown in FIG. 5 , in another embodiment of the present application, aspecific charging method is provided, and the method may be applied tothe fast charging system described in FIG. 1 . The method includes thefollowing steps.

S401. A terminal 10 detects a voltage signal of a communication cable toobtain a charging mode supported by a charger 20. It should be notedthat the communication cable connects the terminal 10 and the charger20.

S402. When the charging mode supported by the charger 20 includes anopen-loop fast charging mode, the terminal 10 is adjusted to an openloop state, and sends an open-loop fast charging instruction to thecharger 20, so that the charger 20 outputs a voltage and a current inthe open-loop fast charging mode.

S403. When detecting that a battery voltage value of the terminal 10 isgreater than a first preset threshold and the charging mode supported bythe charger 20 includes a closed-loop fast charging mode, the terminal10 adjusts the charging mode from the open-loop fast charging mode tothe closed-loop fast charging mode, and performs charging according tothe detected battery voltage value, a charging current, and a pre-storedcharging curve.

It should be noted that when the battery voltage value of the terminal10 reaches a third preset threshold (the third preset threshold is closeto a voltage value of a battery in a fully charged state, for example,may be 99% of the voltage value of the battery in the fully chargedstate), the charger 20 is notified to stop charging.

As shown in FIG. 6 , in another embodiment of the present application, aspecific charging method is provided, and the method may be applied tothe fast charging system described in FIG. 1 . The method includes thefollowing steps.

S501. A terminal 10 detects a voltage signal of a communication cable toobtain a charging mode supported by a charger 20. It should be notedthat the communication cable connects the terminal 10 and the charger20.

S502. When the charging mode supported by the charger 20 includes anopen-loop fast charging mode, the terminal 10 is adjusted to an openloop state, and sends an open-loop fast charging instruction to thecharger, so that the charger 20 outputs a voltage and a current in theopen-loop fast charging mode.

S503. When detecting that a battery voltage value of the terminal 10 isgreater than a second preset threshold and the charging mode supportedby the charger 20 includes a common charging mode, the terminal 10adjusts the charging mode from the open-loop fast charging mode to thecommon charging mode, and performs charging in the common charging mode.

It should be noted that the common charging mode may be another modeother than the open-loop fast charging mode and a closed-loop fastcharging mode.

A first preset threshold and the second preset threshold may be thesame, or may be different.

For example, in the common charging mode, the charger may provide 5V/0.5 A, 9 V/1 A, or the like, and this is not enumerated one by oneherein.

It should be noted that when the battery voltage value of the terminal10 reaches a third preset threshold (the third preset threshold is closeto a voltage value of a battery in a fully charges state, for example,may be 99% of the voltage value of the battery in the fully chargedstate), the charger 20 is notified to stop charging.

The following describes in detail a terminal 10 in a fast chargingsystem (as shown in FIG. 1 ) according to an embodiment of the presentapplication with reference to FIG. 7 . The terminal 10 includes anobtaining unit 610, a detection unit 620, a sending unit 630, areceiving unit 640, and a charging unit 650.

The obtaining unit 610 is configured to obtain a charging mode supportedby a charger connected to the terminal 10.

It should be noted that the obtaining unit 610 may determine, bydetecting a voltage signal of a communication cable between the terminaland the charger, the charging mode supported by the charger.

Optionally, the terminal 10 may obtain, by means of interaction, thecharging mode supported by the charger. For example, the sending unit630 sends a request message to the charger connected to the terminal,where the request message is used to obtain the charging mode supportedby the charger. The obtaining unit 610 is configured to receive afeedback message sent by the charger, where the feedback messageincludes the charging mode supported by the charger.

The detection unit 620 is configured to: when the charging modesupported by the charger 20 includes an open-loop fast charging mode,detect, by the terminal, whether both the terminal and the charger arein an open loop state.

The sending unit 630 is configured to: when both the charger 20 and theterminal 10 are in the open loop state, send, by the terminal, anopen-loop fast charging instruction to the charger.

It should be noted that the open-loop fast charging instruction mayinclude different parameters to instruct the charger 20 to transmit avoltage and a current. For example, the open-loop fast charginginstruction includes a battery voltage value and a target voltage valueof the terminal, and the open-loop fast charging instruction is used toinstruct the charger to output a voltage of the target voltage value andoutput a current according to the battery voltage value.

For another example, the open-loop fast charging instruction includes atarget voltage value and a target current value, and the open-loop fastcharging instruction is used to instruct the charger to output a voltageof the target voltage value and a current of the target current value.

For another example, the open-loop fast charging instruction includes abattery voltage value of the terminal, and is used to instruct thecharger to output a voltage and a current according to the batteryvoltage value. It should be noted that the battery voltage value may bedetected by using a detection circuit. As shown in FIG. 8 , in aspecific detection circuit for detecting a battery voltage of a terminal(mobile phone), a switch Qb is connected in series to a battery. Duringcharging, the switch Qb is connected. When the battery voltage isdetected, the switch Qb is disconnected. Both a charging current and adischarging current are 0, so that a voltage drop of a cable and avoltage drop of internal resistance drop to the minimum, and at the sametime, a Qd is connected. The battery voltage is divided by R1 and R2 andsent to a back-end analog-to-digital converter or a comparator, toobtain the battery voltage value.

The receiving unit 640 is configured to receive the voltage and thecurrent that are transmitted by the charger 20 according to theopen-loop fast charging instruction, and in a specific implementation,the receiving unit 640 may receive, by using a receiving circuit, theoutput voltage and the output current that are transmitted by thecharger.

The charging unit 650 is configured to perform charging in the open-loopfast charging mode.

It should be noted that the charging unit 650 is specifically configuredto: convert the received voltage into a 1/K times output voltage, andconvert the received output current into a K times output current, wherea conversion coefficient K is a constant value, and K is any real numbergreater than 1; and the charging unit 650 is further configured tocharge the battery according to the 1/K times output voltage and the Ktimes output current.

It should be noted that optionally, the charging unit 650 includes aconversion circuit and a charging circuit. The conversion circuit isconfigured to convert the received voltage into the 1/K times outputvoltage, and convert the received output current into the K times outputcurrent. The charging circuit performs charging in the open-loop fastcharging mode. Optionally, the conversion circuit is a Buck circuit or aswitched capacitor conversion circuit.

For example, as shown in FIG. 9 , the conversion circuit uses a buckmanner with a fixed duty cycle. In a buck with a fixed duty cycle,switching transistors Q1 and Q2 form a bridge arm. Drive signals V1 andV2 drive Q1 and Q2 to be alternately connected, so as to convert adirect current voltage Vin into a pulse voltage with a fixed duty cycle,and implement a voltage drop with K times conversion coefficient. Adirect current voltage Vout is output after filtering performed by aninductor L3, and Vout=Vin/K. A duty cycle is fixed to a maximum value,and charging can be efficiently performed. In addition, in the buckmanner with a fixed duty cycle, a plurality of bucks may be connected inparallel according to a phase sequence to form a multiphase buck.

For example, as shown in FIG. 10 , a DC/DC conversion module may furtheruse a switched capacitor converter. Four switching transistors areconnected in series in the switched capacitor converter. A capacitor C7is connected between a midpoint of Q1 and Q2 and a midpoint of Q3 andQ4. V2 to V5 are drivers of the switching transistors. V2 and V5 arecomplementary, and V3 and V4 are complementary. A 2:1 switched capacitorconverter may drop an input voltage to half of the input voltage at afixed ratio of 2:1. After Vin is converted by the conversion circuit, avoltage Vout≈Vin/2 is output. Switched capacitor conversion requires noinductor, and a loss can be greatly reduced. Therefore, conversionefficiency can be greatly improved, and a larger charging current can beimplemented.

Optionally, it should be noted that the terminal further includes aswitching unit 660.

The detection unit 620 is further configured to: when the charging modesupported by the charger further includes a closed-loop fast chargingmode, detect a voltage of the battery in the terminal to obtain thebattery voltage value.

The sending unit 630 is configured to: when the battery voltage value isgreater than a first preset threshold, send a closed-loop fast charginginstruction to the charger.

The receiving unit 640 is further configured to receive a voltage and acurrent that are transmitted by the charger according to the closed-loopfast charging instruction.

The switching unit 660 is configured to switch the charging mode fromthe open-loop fast charging mode to the closed-loop fast charging mode.

The charging unit 650 is configured to perform charging in theclosed-loop fast charging mode.

Optionally, it should be noted that the detection unit 620 is furtherconfigured to: when the charging mode supported by the charger furtherincludes the common charging mode, detect a voltage of the battery inthe terminal to obtain the battery voltage value.

The sending unit 630 is configured to: when the battery voltage value isgreater than a second preset threshold, send a common charginginstruction to the charger.

The receiving unit 640 is configured to receive a voltage and a currentthat are transmitted by the charger according to the common charginginstruction.

The charging unit 650 is configured to perform charging in the commonfast charging mode.

It can be learned from the foregoing that the terminal provided in thepresent application identifies the charging mode supported by thecharger. When the charger can support open-loop fast charging, theterminal switches to the open loop state, uses the fixed duty cycle towork, and continuously adjusts the output voltage and the output currentof the charger based on real-time voltage feedback of the battery, so asto shorten a charging time and achieve an objective of fast charging.

As shown in FIG. 11 , a charger 20 in the fast charging system includesa handshake unit 1010, a receiving unit 1020, and an output unit 1030.

The handshake unit 1010 is configured to: when the charger 20 detectsthat a connection is established to a terminal 10, perform a handshakewith the terminal 10, so that the terminal 10 determines that thecharger 20 supports an open-loop fast charging mode.

It should be noted that the handshake unit 1010 may set a voltage signalof a communication cable, so that the terminal determines, according tothe voltage signal, that the charger supports the open-loop fastcharging mode.

In addition, the charger may notify, by means of interaction, theterminal 10 of the charging mode supported by the charger 20. Forexample, the receiving unit 1020 receives an inquiry request sent by theterminal, where the inquiry request is used to obtain the charging modesupported by the charger. The handshake unit 1010 sends, when thereceiving unit receives the inquiry request, feedback information to theterminal, where the feedback information is used to indicate that thecharger supports a fast charging mode.

The receiving unit 1020 is configured to receive instruction informationsent by the terminal 10.

The output unit 1030 is configured to: when the instruction informationis used to instruct the charger 20 to charge in the open-loop fastcharging mode, output a voltage and a current according to theinstruction information in the open-loop fast charging mode.

It may be understood that the instruction information may instruct, indifferent manners, the charger 20 to adjust the voltage and an outputcircuit.

For example, the instruction information includes a battery voltagevalue of the terminal, and the output unit 1030 includes an adjustmentcircuit and a transmission circuit.

The adjustment circuit is configured to adjust the voltage to K timesthe battery voltage value.

The output circuit is configured to output a voltage of the K times thebattery voltage value, where K is a pre-stored fixed conversion ratiocoefficient, and K is a constant value and is any real number greaterthan 1.

The adjustment circuit is further configured to determine a currentcorresponding to the battery voltage value.

The output circuit is further configured to output the currentcorresponding to the battery voltage value, where a correspondencebetween the battery voltage value and the current is pre-stored in thecharger.

For another example, the instruction information includes a batteryvoltage value and a target voltage value of the terminal.

The adjustment circuit is configured to adjust the voltage to the targetvoltage value.

The output circuit is configured to output a voltage of the targetvoltage value.

The adjustment circuit is further configured to determine a currentvalue corresponding to the battery voltage value.

The output circuit is further configured to output the currentcorresponding to the battery voltage value, where a correspondencebetween the battery voltage value and the current is pre-stored in thecharger.

For another example, the instruction information includes the targetvoltage value and a target current value.

The adjustment circuit is configured to adjust the voltage to the targetvoltage value. The output circuit is configured to output a voltage ofthe target voltage value.

The adjustment circuit is further configured to adjust the outputcurrent to the target current value. The output circuit is furtherconfigured to output a current of the target current value.

As shown in FIG. 12 , an embodiment of the present application providesanother fast charging system. The fast charging system includes acharger and a terminal (a mobile phone is used as an example). It shouldbe noted that the charger has a function of outputting a fixed directcurrent voltage, or has a function of adjusting an output voltage or anoutput current according to a battery voltage of the terminal or a stateof charge of a battery.

The charger includes an AC/DC conversion module, a charging controlmodule, a communications module, and a storage module.

The AC/DC conversion module is configured to convert, into a directcurrent, an alternating current provided by an alternating current powersupply.

It should be noted that, if the charger is connected to a direct currentpower supply, the charger may also include a DC/DC conversion module.

The communications module is configured to interact with the terminal,so that the terminal determines that the charger supports an open-loopfast charging mode; or the communications module is configured tointeract with the terminal, so that the charger determines that theterminal supports an open-loop fast charging mode.

For example, the communications module may transmit charger or batteryinformation, current and voltage information, temperature information,and a command. For example, a charging current amplitude is determinedby using different voltage combinations on two cables D+ and D− of aUSB: Voltages of D+ and D− may be classified into m levels, and m*mcurrent values may be determined; or transmission is performed by usinga digital signal, and so on.

The communications module is configured to: when receiving an open-loopfast charging command sent by the terminal, send an instruction to thecharging control module.

The charging control module is configured to: adjust the output voltageaccording to the instruction sent by the communications module, andoutput the output current corresponding to the instruction. Acorrespondence between the instruction and the current is stored in thestorage module.

The mobile phone includes a DC/DC conversion module, a battery module, abattery detection module, and a charging management module.

The DC/DC conversion module in the mobile phone may work in an open loopstate, or may work in a closed loop state. The DC/DC conversion modulein the mobile phone may be a switched capacitor converter, a criticalmode soft switch Buck converter, or another converter, and this is notenumerated one by one herein.

It should be noted that when the DC/DC conversion module works in theopen loop state, the DC/DC conversion module converts the receivedvoltage and the received current according to a fixed conversion ratio.

Further, it should be noted that the DC/DC conversion module has atleast two working modes, and may work in the closed loop state or theopen loop state. Specifically, the DC/DC conversion module works in acorresponding mode according to a working mode supported by the charger,and achieves a maximum charging current or an optimal efficiency effect.

Further, when it is detected that the charger supports open loop modecharging, the DC/DC conversion module of the mobile phone works in theopen loop state. When the charger does not support the open loop modecharging, correspondingly, the DC/DC conversion module of the mobilephone works in the closed loop state.

As shown in FIG. 13 , a switched capacitor converter is used as anexample. When a mobile phone communicates with a charger and determinesthat the charger supports an open-loop fast charging mode, a switchingtransistor of the switched capacitor converter works in a fixedfrequency and fixed duty cycle state. A phase difference between Q1 andQ4 is 180°, and a duty cycle is approximately 50% (there is a deadzone). A phase difference between Q2 and Q3 is 180°, a duty cycle isapproximately 50% (there is a dead zone). A phase difference between Q1and Q2 is 180°. In this case, a charging current and a charging voltageof a battery are controlled by the charger by adjusting an outputvoltage.

When the mobile phone communicates with the charger and determines thatthe charger does not support the open-loop fast charging mode, theconverter works in the closed loop state, and there may be two specificcontrol manners.

(A) Q1 and Q4 are directly connected.

A circuit is simplified as a buck circuit. Drive signals of Q2 and Q3are complementary, and there is the dead zone.

The charging voltage and the charging current are controlled byadjusting the duty cycle.

(B) Q1 and Q4 are complementary, and Q2 and Q3 are complementary.

The phase difference between Q1 and Q2 is 180°, and the charging voltageand the charging current are controlled by adjusting the duty cycle.When the converter works in the closed loop state, the chargingmanagement module of the mobile phone has a preset value of the chargingcurrent and a preset value of the charging voltage, and the DC/DCconversion module adjusts the charging voltage and the charging currentaccording to the preset values, to complete a charging process.

The battery detection module is configured to detect a battery voltage.It may be understood that when the battery detection module detects thebattery voltage, charging may be stopped or the charging current may bereduced, to ensure detection precision.

The battery detection module may further obtain a battery current, astate of charge of the battery, a health state, and the like.

The charging management module includes a communications module, a modeselection module, and a storage module, and the like, and is configuredto interact with the charger, supply power to the mobile phone, andmanage charging mode selection.

It should be noted that an entire charging process of the fast chargingsystem includes pre-charging (a battery voltage is less than 3 V), fastcharging (a battery voltage is greater than 3 V and less than 4.2 V),slow charging (a battery voltage is greater than 4.2 V and less than 4.5V), and numbers in brackets are used for example description.

It should be further noted that a process, after the charging modesupported by the charger is determined and a charging mode supported bythe terminal is determined, may be led by the charger, or may be led bythe terminal.

For example, the charger inquires about, by sending information, thecharging mode supported by the terminal. When the charging modesupported by the terminal includes the open-loop fast charging mode, thecharger determines whether the charger also supports the open-loop fastcharging mode. When the charger also supports the open-loop fastcharging mode, the charger instructs the terminal to start open-loopfast charging.

On the contrary, the terminal may inquire about, by sending information,the charging mode supported by the charger. When the charging modesupported by the charger includes the open-loop fast charging mode, theterminal determines whether the terminal also supports the open-loopfast charging mode. When the terminal also supports the open-loop fastcharging mode, the terminal instructs the charger to start open-loopfast charging.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of the present application.

It may be clearly understood by a person skilled in the art that, forease and brevity of description, for a detailed working process of theforegoing system, apparatus, and unit, refer to a corresponding processin the foregoing method embodiments, and details are not describedherein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual requirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentapplication may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit.

When the functions are implemented in the form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of the present applicationessentially, or the part contributing to the prior art, or some of thetechnical solutions may be implemented in a form of a software product.The software product is stored in a storage medium, and includes severalinstructions for instructing a computer device (which may be a personalcomputer, a server, or a network device) to perform all or some of thesteps of the methods described in the embodiments of the presentapplication. The foregoing storage medium includes: any medium that canstore program code, such as a USB flash drive, a removable hard disk, aread-only memory (ROM), a random access memory (RAM), a magnetic disk,or an optical disc.

The foregoing descriptions are merely specific implementations of thepresent application, but are not intended to limit the protection scopeof the present application. Any variation or replacement readily figuredout by a person skilled in the art within the technical scope disclosedin the present application shall fall within the protection scope of thepresent application. Therefore, the protection scope of the presentapplication shall be subject to the protection scope of the claims.

1. A charging method, wherein the method comprises: in response to acharger detecting that a connection is established to a terminal,performing, by the charger, a handshake with the terminal, wherein theterminal determines that the charger supports an open-loop fast chargingmode; receiving, by the charger, instruction information sent by theterminal; and in response to determining that the instructioninformation is used to instruct the charger to charge in the open-loopfast charging mode, outputting, by the charger, a voltage and a currentaccording to the instruction information in the open-loop fast chargingmode.
 2. The method according to claim 1, wherein the performing, by thecharger, a handshake with the terminal comprises: setting, by thecharger, a voltage signal of a communication cable, wherein the terminaldetermines, according to the voltage signal, that the charger supportsthe open-loop fast charging mode.
 3. The method according to claim 1,wherein the performing, by the charger, a handshake with the terminalcomprises: receiving, by the charger, an inquiry request sent by theterminal, wherein the inquiry request is used to obtain a charging modesupported by the charger; and sending, by the charger, feedbackinformation to the terminal, wherein the feedback information is used toindicate that the charger supports a fast charging mode.
 4. The methodaccording to claim 1, wherein the instruction information comprises abattery voltage value of the terminal; and wherein the outputting, bythe charger, a voltage and a current according to the instructioninformation in the open-loop fast charging mode comprises: adjusting, bythe charger, the voltage to K times the battery voltage value, wherein Kis a pre-stored fixed conversion ratio coefficient, and K is a constantvalue and is any real number greater than 1; determining, by thecharger, a current corresponding to the battery voltage value, wherein acorrespondence between the battery voltage value and the current ispre-stored in the charger; and outputting, by the charger, a voltage ofthe K times the battery voltage value, and outputting the currentcorresponding to the battery voltage value.
 5. The method according toclaim 1, wherein the instruction information comprises a battery voltagevalue of the terminal and a target voltage value of the terminal; andwherein the outputting, by the charger, a voltage and a currentaccording to the instruction information in the open-loop fast chargingmode comprises: adjusting, by the charger, the voltage to the targetvoltage value; determining, by the charger, a current valuecorresponding to the battery voltage value, wherein a correspondencebetween the battery voltage value and the current is pre-stored in thecharger; and outputting, by the charger, a voltage of the target voltagevalue, and outputting the current corresponding to the battery voltagevalue.
 6. The method according to claim 1, wherein the instructioninformation comprises a target voltage value and a target current value;and wherein the outputting, by the charger, a voltage and a currentaccording to the instruction information in the open-loop fast chargingmode comprises: adjusting, by the charger, the voltage to the targetvoltage value; adjusting, by the charger, the current to the targetcurrent value; and outputting, by the charger, a voltage of the targetvoltage value and a current of the target current value.
 7. A charger,wherein the charger comprises: a handshake unit configured to: inresponse to the charger detecting that a connection is established to aterminal, perform a handshake with the terminal, wherein the terminaldetermines that the charger supports an open-loop fast charging mode; areceiver configured to receive instruction information sent by theterminal; and an output unit configured to: in response to determiningthat the instruction information is used to instruct the charger tocharge in the open-loop fast charging mode, output a voltage and acurrent according to the instruction information in the open-loop fastcharging mode.
 8. The charger according to claim 7, wherein thehandshake unit is further configured to set a voltage signal of acommunication cable, and wherein the terminal determines, according tothe voltage signal, that the charger supports the open-loop fastcharging mode.
 9. The charger according to claim 8, wherein: thereceiver is further configured to receive an inquiry request sent by theterminal, wherein the inquiry request is used to obtain a charging modesupported by the charger; and the handshake unit is further configuredto send feedback information to the terminal, wherein the feedbackinformation is used to indicate that the charger supports a fastcharging mode.
 10. The charger according to claim 7, wherein theinstruction information comprises a battery voltage value of theterminal; wherein the output unit is configured to: adjust the voltageto K times the battery voltage value, and output a voltage of the Ktimes the battery voltage value, wherein K is a pre-stored fixedconversion ratio coefficient, and K is a constant value and is any realnumber greater than 1; and determine a current corresponding to thebattery voltage value, and output the current corresponding to thebattery voltage value, wherein a correspondence between the batteryvoltage value and the current is pre-stored in the charger.
 11. Thecharger according to claim 7, wherein the instruction informationcomprises a battery voltage value of the terminal and a target voltagevalue of the terminal; wherein the output unit is configured to: adjustthe voltage to the target voltage value, and output a voltage of thetarget voltage value; and determine a current value corresponding to thebattery voltage value, and output the current corresponding to thebattery voltage value, wherein a correspondence between the batteryvoltage value and the current is pre-stored in the charger.
 12. Thecharger according to claim 7, wherein the instruction informationcomprises a target voltage value and a target current value; wherein theoutput unit is configured to: adjust the voltage to the target voltagevalue, and output a voltage of the target voltage value; and adjust thecurrent to the target current value and output a current of the targetcurrent value.
 13. A charging system, wherein the charging systemcomprises a connection cable, a terminal, and a charger, wherein theterminal is connected to the charger by using the connection cable, andwherein the charger is configured to: in response to detecting that aconnection is established to the terminal, perform a handshake with theterminal, wherein the terminal determines that the charger supports anopen-loop fast charging mode; receive instruction information sent bythe terminal; and in response to determining that the instructioninformation is used to instruct the charger to charge in the open-loopfast charging mode, output a voltage and a current according to theinstruction information in the open-loop fast charging mode.
 14. Thecharging system according to claim 13, wherein the charger sets avoltage signal of the connection cable, and wherein the terminaldetermines, according to the voltage signal, that the charger supportsthe open-loop fast charging mode.
 15. The charging system according toclaim 13, wherein the charger receives an inquiry request sent by theterminal and sends feedback information to the terminal, wherein theinquiry request is used to obtain a charging mode supported by thecharger, and wherein the feedback information is used to indicate thatthe charger supports a fast charging mode.
 16. The charging systemaccording to claim 13, wherein the instruction information comprises abattery voltage value of the terminal, and wherein the charger isconfigured to: adjust the voltage to K times the battery voltage value,and output a voltage of the K times the battery voltage value, wherein Kis a pre-stored fixed conversion ratio coefficient, and K is a constantvalue and is any real number greater than 1; and determine a currentcorresponding to the battery voltage value, and output the currentcorresponding to the battery voltage value, wherein a correspondencebetween the battery voltage value and the current is pre-stored in thecharger.
 17. The charging system according to claim 13, wherein theinstruction information comprises a battery voltage value of theterminal and a target voltage value of the terminal, and wherein thecharger is configured to: adjust the voltage to the target voltagevalue, and output a voltage of the target voltage value; and determine acurrent value corresponding to the battery voltage value, and output thecurrent corresponding to the battery voltage value, wherein acorrespondence between the battery voltage value and the current ispre-stored in the charger.
 18. The charging system according to claim13, wherein the instruction information comprises a target voltage valueand a target current value, and wherein the charger is configured to:adjust the voltage to the target voltage value, and output a voltage ofthe target voltage value; and adjust the current to the target currentvalue and output a current of the target current value.
 19. A chargingmethod, wherein the method comprises: obtaining, by a charger, acharging mode supported by a terminal connected to the charger; inresponse to determining that the charging mode supported by the terminalcomprises an open-loop fast charging mode, detecting, by the charger,whether both the terminal and the charger are in an open loop state; inresponse to determining that both the terminal and the charger are inthe open loop state, obtaining, by the charger, a charging parameter ofthe terminal; and adjusting, by the charger, a voltage and a currentaccording to the charging parameter, and transmitting, to the terminal,an adjusted voltage and an adjusted current.